Airplane retractable landing gear locking and signaling means



, Aug. 11, 1942 P. A. SUMNER ET AL 2,292,671 AIRPLANE RETRACTABLELANDING GEAR LOCKING AND SIGNALING MEANS ,Filed Oct. 9, 1940 3Sheets-Sheet 1 INVENTORS AUA A; SUMNER AND JA CK y/S/QFEA/ NEY5 ' Aug.11, 1942. P. A. SUMNER ETAL 2,292,671 GEAR LOCKING AND SIGNALING MEANS.

AIRPLANE RETRACTABLE LANDING Filed 001;. 9, 1940 s sheets-sheet 2INVENTORS UMNER P404 ,4 5 AM) JAC /5REEL/,'

. AT r RNEYS 1942- P. A. SUMNER E v AIRPLANE RETRACTABLE LANDING GE ARLocxme AND SIGNALING MEANS 3 Sheets-Sheet 3 Y m w Q \w v a n Q H m mPatented Aug. 11, 1942 v UNITED STATE s PATENT, OFFICE AI PLANERETRACTABLE LANDING GEAR LocmN AND SIGNALING MEANS aul A. Sumner, LongIsland, and Jack Isreeli, New York, N. Y., assignors to BrewsterAeronautical Corporation, Long Island City, N. Y. Application October 9.1940, Serial No. 360,442

6 Claims. (oi. 244-102) Fig. 1 is a, fragmentary front elevation of anairplane landing gear structure of the inven-= tion;

Fig. 2 is a fra tion of Fig. 1;

Fig. 3 is' an enlarged view of a detail of Fig. 1; Fig. 4 is a section,on an enlarged scale, taken substantially along line V--V of Fig. 3;

gmentary side elevation of a portype and comprises generally telescopicmembers 40 and 42 which are adapted to move axially rel- Fig. 5 is asection, on an enlarged scale, taken.

substantially along line V-V of Fig. 3; and

Fig. 6 is a diagrammatic view of remote control and signal devicesassociated with the mechanism illustrated by the other figures. g

The drawings illustrate the invention .incon-- 10 upon which is mounteda landing wheel car as carrying a landing wheel l4 and asbein pivotallymounted at its upper end upon the .win panel In by means of pivot pins18. A fold;

type strut I8 is pivotally connected by mean of a pin to an intermediateportion ofth strut I2 and by means of apin 22toa fixed portion-of thewing panel l0 so as to be adapted to function as a lateral brace for themain strut l2 when the gear is in extended position. The strut- I8 ishinged asat 24 so as to be adapted to break away from the pivotalconnection I'S- -l 6, and a. hydraulic jack 26 is operatively connectedat one end by means of a pin 28 to a crank arm 30. extending rigidlyfrom the upper end. of the main strut .l2. The jack 26 is operativelyconnected at its opposite end, by means of a connection device 32 to oneof the elements of the folding strut [8 at apoint intermediately of thepivotal connections 20-'-22. Consequently, the hydraulic jack is adaptedto'be actuated by ative to one another under airplane landing forces tocushion the effects of such forces, and a pair of articulated links 44are pivotally connected to the telescopic members 40 and 42 to provide aso-called scissors connection therebetween for maintaining the membersin radial alignment. (Figs. 2 and 4.) J

A lock device for maintaining the retraction actuating elements of thegear is indicated gen- ,erally by the numeral in Fig. 1 and shown indetail in Figs. 3 .and 5. The lock device 50.

is mounted upon a bracket device 52 extending from a, stationary portionof the wing panel, and operating elements thereof are arranged inassociation with t'he upper element of the folding strut lB in suchmanner as to.detachably connectit to the bracket 52 for locking theairplane landing gear in its extended position. For this 'purposethe'locking device comprises essentially a latch 54 which is pivotallymounted upon a, fixed bracket 56' extending laterally from the nectionwith an airplane having a wing panel'f rying main strut l2. The strut I2is illustrated means'of hydraulic pressure so as to extend itself and tobear in opposite directions against themain strut crank arm 30 andagainst the folding strut about its hinge 24 and to cause goes my;

T engagement with the bracket 5 folding strut la in such manner as tobreak the I shock absorbing folding'strut' l8;: the pivotable mountingof the latch being provided by a pin 58 extending through the latchandthe bracket 56. The latch member 54-ls recessed at 60 at one sidethereof for locking engagement. with a pin 62 extendn fixed relationfrom the bracket 52. A ion spring is connected to the latch 54 at antimes urge the latch into locking respect to the pin52; and a stop slaterally from'the latch 54 for 6,to limit 'the' movement of the latch54 inresponse to the so'that the latch remains in proper gagement of thefixed pin 62 relation with P n"; 65 extend spring forces attitude forreen whenever the lan stop pin 55"is eccentrically mounted upon thelatch 54 so vas to be rotatable to different positions of adjustment soas to minutely adjust the limit of the spring action as may be requiredupon final assembly ofthe mechanism.

1 A release device for the latch 54 is provided in the form of a crank10 pivotally'mounted upon the bracket 52 by means of a pin 12 and havingan end portion in sliding abutting relation with respect to an endportion 14 of the latch 54 for 1 pivoting the latter upon the pin 58againstthe action of the spring 54 in such manner as to removethe latch54 from engagement with the pin 62. A control cable I6 is'connectedtothe era k ll! insuch manner as-to be adapted to be pulled to move thecrank 10 so as to release'the latch as described hereinabove. I A coilspring; l8

ding gear is retracted. The I is mounted upon the pin I2 so as to at alltimes resiliently urge the crank away from engagement with the arm I4 ofthe latch. The control cable I6 is threaded over a pulley 80 mountedupon a fixed portion of the wing panel and is connected at its oppositeend to a pilot control lever 82 disposed within convenient reach of theairplane pilot (Fig. 6). The lever 82'is also operatively connected tothe hydraulic jack control valve 84 which controls the fiow of fluidpressure to the hydraulic jack 26 for actuating the landing gear. Thecontrol devices are so arranged that upon pilot manipulation of thecontrol lever 82 from the position illustrated in Fig. 6 toward theright as viewed in the drawing, the control cable 16 will be pulled tomove the crank I against the latch finger I4 so as to release the latch54from engagement with the fixed pin'62. Simultaneously, the movement ofthe pilot control lever 82 will actuate the valve 84 so as to introducefluid pressure into the hydraulic jack 26 in such manner as to cause thelatter to extend and to bear laterally against .the folding strut I8 forretraction of the landing gear as explained hereinabove. v

The parts of the mechanism are so arranged that the axis of the pivot 58is outside, or to the right as viewed in Fig. 3, of a line drawn normalto the radius of rotation of the latching g a about the pivot pin 22where it intersects the axis of the fixed pin 62. Hence, wheneverthe'landing gear is locked in its extended position, asillustrated inFig. 3, external forces acting upon the landing gear tending to move thefolding strut I8 away from the locking bracket 52 will react to andthreaded about a pulley I02 which is carried by the pin 22 defining thepivotal axis of the folding 'strut element I8. The cable I00 is thencethreaded around a pulley I04 which is illustrated as being mountedparallel to the pulley 80 hereinabove described and upon a fixed portionof the airplane wing panel. From the pulley I04 the cable I00 leadsforwardly to a 'visual indicator device located within convenient viewof the pilot when seated in the airplane cockpit (Fig. 6); the cable I00being wrapped about a drum I06 rotatably carried upon a fixed wallportion of the airplane and at all times urged by a coil spring I08 torotate so as to pull the cable I00 forwardly. By reason of the threadingof the cable I00 about the pulley I02, the cable I00 is relaxed from thecondition illustrated in the figures and allowed to be pulled forwardlyby the coil spring I08 whenever the landing gear strut I8 is movedtoward gear retracted position from the position illustrated in Figs. 1and 3. An indicator finger H0 is fixed to the cable I 00 so as 'to move,therewith and to register with scale markings indicated in Fig. 6 todesignate the condition of the landing gear mechanism throughouttherange of its various adjustments.

In this respect particular attention is called to the fact that wheneverthe landing gear is moving from retracted toward extended position, thecable I00 will move the indicator finger IIO from the dial positionmarked up toward the dial move the latch toward more firmly lockedposi-- spaced from the adjacentcenter 96 of pivotal connection of thelink to the strut element 40. The parts are so proportionedand'relatively arranged that whenever the weight of the airplane isdisposed upon the landing gear and the telescopic members 40 and 42 arein relatively retracted position, the cable 92 will be pushed upwardly'sufficiently to move the hook 90 to the position thereof illustrated inFig. 3 wherein it engages a pin 98 extending transversely from the latchmember 54. Consequently, when the airplane is resting upon the landingsurface the hook 90 will prevent the pilot from releasing the landinggear lock and motivating the hydraulic jack control valve. Upon take-offof the airplane, however, the relative extension of the landing geartelescopic elements 40 and 42 upon release of the weight of the airplanetherefrom will open the scissors links 44 in such manner as topull'downwardly upon the cable 92 so as to withdraw the hook 90 fromassociation with the latch pin. Thus, the locking device is then freedto be actuated by the remote control means as the pilot may desire.

A pilot signal device for indicating the condition of the airplanelanding gear and the locking device 50 is provided through means of acable I00 conected at one end to the latch 54 position marked down, andthat as the strut I8 assumes its straightened final gear extendedpositionthe finger portion I4 of the latch 54 cams over the fixed pin 62until the recessed portion 60 of the latch registers with the pin 62,whereupon the latch finally snaps downwardly under the action of thespring 64 into locking engagement with the pin 62 without furthercorresponding movement of the strut I8, and there- I by pulls the cableI00 from the dial position marked down"- -to the dial position marked"down and locked." Thus, the dial provides at all times a; visibleindication of the position of the landing gear and of the condition ofthe locking device 50.

An additional signal actuating device in the form of a micrometer switchH2 is shown in Fig.-

3 as being mounted, upon afixed portion of the airplane wing panel andhaving an actuating finger II4 extending into registry with the lookinglatch 54 so as to be adapted to close an electrical circuit to a soundor lighhsignal whenever the latch 54 is withdrawn-fibhl' lockingposition with respect to the fixed'pin '62. Consequently, an audible orlight signal will be thereby activated as the landing gear movesbetween. extended and retracted positions; a similar micrometer switchbeing preferably provided adjacent the retarded position of the enginethrottle for again opening the signal control circuit when the enginespeed is above safe flying speed. Thus, an additional safety device isprovided for reminding the pilot that the landing gear is not locked inextended position whenever the throttle is retardedbelow fiying speed.

Although-onlvone form of the invention has been shown and described indetail, it will be apparent to those skilled in the art that theinvention is not so limited but that. various changes may bemade'therein without departing from the spirit of the invention or thescope of the appended claims.

a What is claimed is:

1. In an airplane, a retractable landing gear,

gear to a fixed portion of said a movable member associated with saidgear,

saidlatch against releasing movement with respect to said movable memberwhen said landing gear is extended and in pressure contact with alanding surface, and means associated with said hook device for movingthe latter to latch of said gear, and a hook devicearranged to holdrelease position whenever said landing gear is relieved of pressurecontact relative to a landing surface.

2 In an airplane, a retractable landing gear compris ng a main strut oftelescoping force absorbing form, a movable member associated with saidgear, means for moving said movable memher to actuate said gear fromextended to retracted positions, a latch normally locking said airplanewhen said gear is in extended position, remotely controlled means forreleasing said latch, means operatively connecting said latch controlmeans and said movable member moving means in such manner that releaseof said latch is automatically accompanied by movement of said movablemember so as to procure retraction of said gear, a hook device arrangedto hold said latch against releasing movement with respectto saidmovable .member when said landing gear is extended and supporting saidairplane upon a landing surface, and means operatively connected with atelescop-' ing. portion element-0f said landing gear main strut and saidhook for moving the latter to latch release position whenever saidlanding gear is relieved of pressure contact relative to a landingsurface.

3. In an airplane. a retractable landing gear,

a a movable member associated. with said gear,

means for moving said movable member, a latch pivotally mounted uponsaid movable member and normally locking saidfgear to a' fixed portionof said airplane when said gear is in extended position, remotelycontrolled means for releasin said latch, means operatively-connectingsaid latch control means and said movable member moving means in suchmanner that released said latch is automatically accompanied bymovementof said movable member so asto procure retraction of said gear,and means operatively connected to said latch to indicate visually thecondition of the landing gear movable member and of said latch at aposition remote therefrom.

4. In an airplane, aretractable landing gear having a member movable toactuate said gear between extended and contracted positions, means formoving said movable member, a latch pivotally mounted upon saidmovablemember and normally locking said movable member in connection with afixed portion of said airplane when said gear is in extended position,remotely controlled-means for releasing saidlatch, a hook devicearranged to move so as to engage said latch against releasing movementwith respect to said movable member when said landing gear tact relativeto a landing surface, said latchhavis in fully extended position andsupporting said airplane in pressure contact upon a landing surface,means operatively connecting said movable member and Said latch to aremotely disposed visual indicator to indicate progressively theposition of said movable member between gear'extended and gear retractedpositions and the condition of said latch, said connection means beingadaptedto move said indicator in response to latch movementsindependently of movements of said movable member preparatory to latchhooking movements of said hook.-

5. In an airplane, a retractable landing gear comprising a main strut oftelescoping force absorbing form, a movable member associated with saidgear, means for moving said movable member to actuate said gear betweenextended and retracted positions, a latch normally locking said gear toa fixed portion of said airplane, remotely controlled means forreleasing said latch, means operatively connecting said l'atch controlmeans and said movable member moving means in such manner that releaseof said latch is automatically accompanied by movement of said movablemember, a hook device arranged to hold said latch against releasingmovement with respect to said m0vable member when said landing gear "isextended and supporting said airplane upon a landing surface, and meansoperatively connected with a telescoping portion element of saidlandinggear main strut and said hook for moving thelatter to latch releaseposition whenever said landing gear is relieved of pressure coningits-force bearing portions so arranged relative to said fixed portion ofsaid airplane as to be normally stable inlatched position.

6. In an airplane, a retractable landing gear,

a movable member associated with said gear,'

means for moving said movable member, a latchpivotally mounted upon saidmovable member and normally locking said gear to a, fixed portion ofsaid airplane when said gear is in extended position, remotelycontrolled means for releasing said latch, a hook device arranged tomove so as to engage said latch against releasing movement with respectto said movable member when said landing gear is in fully extendedposition and sup,- porting saidairplane in pressure contact upona'landing surface, means operatively connecting said latch control meansand said movable memher-moving means in such manner that release of saidlatch is automatically accompanied by actuation of said movable member,means operatively connecting said movable member and said latch to aremotely disposed visual indicator to indicate progressively theposition of said movable member between gear extended and gear retractedpositions and the condition of said latch at a position remotetherefrom, said connection means being adapted to move said indicator inresponse to latch movements independently of movements of said movablemember preparatory to latch hooking movements of said hook, and

an audiblesignal device operatively associated with said latch so as toemit soundproducing vibrations whenever said latch is released fromlocking engagement with said movable member.

PAUL A. SUMNER. JACK ISREELI.

